When performing a manufacturing operation on a workpiece, such as a welding or drilling operation, for example, the workpiece is invariably held tightly in place to permit the operation to be carried out with the requisite degree of precision. In some instances, the nature of the workpiece and the type of operation to be performed thereon are such that an operator can simply hold the workpiece with his/her hands while the particular operation is carried out. More often than not, the nature of the workpiece, and the degree of precision required to carry out the operation, are usually such that some type of fixturing is required to rigidly hold the workpiece in place.
Most types of fixtures can classified into two types, those which are manually operated and those which operate automatically. Manually operated fixtures require that a human operator secure the workpiece in the fixture prior to the outset of a manufacturing operation. At the completion of the operation, the operator releases the workpiece and secures another workpiece in the fixture. In contrast, an automatically operated fixture generally functions to grip a workpiece at the outset of a manufacturing operation and thereafter releases the workpiece at the completion of the operation without the need for any intervention by an operator. Manually operated fixtures are usually best suited for low-volume manufacturing when the time required to manually secure and thereafter manually release the part is small as compared to the overall manufacturing operation, whereas automatically operated fixtures are preferred for high-volume operations.
While automatically operated fixtures afford a savings of human labor as compared to manually operated fixtures, automatically operated fixtures do incur a disadvantage in that they typically offer a very limited ability to accommodate dimensional variations in the workpiece being clamped. As a consequence, when a workpiece having minor dimensional variations is clamped by an automatically operated fixture, damage to the workpiece can result. In contrast, with many manually operated fixtures, an adjustment can easily be made by an operator to accommodate dimensional variations in the workpiece being clamped.
Thus, there is a need for an automatically operated fixture which can automatically clamp, so as to conformally grip, a workpiece at the outset of a manufacturing operation to avoid damage to the workpiece during clamping.